"While the millennial homeownership rate continues to decline, it's important to note that the decrease could be just as likely due to new renter household formation as it is their ability to buy homes," said Trulia chief economist Ralph McLaughlin in a note.

But the latest data showed that that homeownership rose in just one category: among 35-44 year olds. Many of these people may have had their homes foreclosed on during the financial crisis, or chose not to buy a home, and are only now entering the market, Zillow's Gudell noted.